This invention relates to methods and apparatus for making stators for electric motors and similar machines such as generators. Although the invention is described herein in the context of its application to electric motor stators, it will be understood that it is equally applicable to other types of stators such as have been mentioned.
Terminal boards for electric motor stators are insulating members which are typically placed on both axial ends of the main stator body for such purposes as supporting the axial ends of the windings wound on the poles of the stator and providing insulated attachment points for the terminals at which the ends of the coil wires can be connected to wires external to the stator.
Recently there has been increasing interest in winding stators without winding forms (see, for example, Wheeler U.S. Pat. No. 4,612,702). This can simplify the winding apparatus and speed the winding process, but it can also increase the strain and wear on the insulating inserts which are typically placed in the stator between circumferentially adjacent poles in order to prevent short circuits between the coils and the stator. Such strain and wear can compromise the insulating effectiveness of the insulating member, possibly resulting in short circuits to the stator. Dislocation or distortion of the insulating member may also occur, possibly resulting in vibration or interference with free rotation of the armature in the finished motor.
In view of the foregoing, it is an object of this invention to provide stator making methods and apparatus, and especially terminal boards, which better protect the associated insulating inserts, especially during winding without winding forms, but even when winding forms are used, if desired.
Another problem which may be exacerbated when winding without winding forms is the possibility that some winding turns in the axial ends of the coils, and especially those winding turns which are intended to fill the area close to the axial end of the stator and in the radially outermost portion of the coil, may not be sufficiently tight or close together to preclude undesirable vibration of those winding turns during operation of the finished motor.
It is therefore another object of this invention to provide stator making methods and apparatus, and especially terminal boards, which promote tight, regular, and complete winding and filling of the stator coils, especially during winding without winding forms, but also when winding forms are used, if desired.
In some electric motor stators the ends of the coil wires (i.e., the so-called start and finish leads) are anchored directly in the terminal receptacles on the terminal board (see, for example, Pearsall U.S. Pat. No. 4,074,418). Metal terminals are then pushed into the receptacles to make electrical contact with the coil wires. In other motors, however, the ends of the coil wires must be held temporarily during and after winding. At a subsequent termination station the ends of the coil wires are relocated to terminals mounted on the terminal board. In the past, the elements for temporarily holding the ends of the coil wires have been provided on the pallets or other structures which support and/or convey the stators (see, for example, Wheeler U.S. Pat. No. 4,612,702, Nussbaumer et al. U.S. Pat. No. 4,679,312, and Santandrea et al. U.S. Pat. No. 4,713,883). Providing elements for temporarily holding the ends of the wire coils on the pallet or other coil supporting structure (hereinafter referred to generically as a pallet) has a number of disadvantages. For one thing, these wire-holding elements complicate the pallet, thereby increasing its cost. The presence of these wire-holding elements around the stator also makes it more difficult to place the stator on or remove the stator from the pallet. The stator-handling elements which perform these tasks must be designed so that they do not interfere with the wire-holding elements. The need for wire-holding elements on the pallet may make it difficult or impossible to use the same pallet for stators of different size (e.g., different stack height). A substantial amount of wire may be needed to temporarily reach wire-holding elements on the pallet. This wire may have to be cut off and discarded when the wire is finally permanently terminated on the terminal board. The fact that the coil ends are temporarily attached to the pallet may make it more difficult or impossible to use certain permanent termination techniques which would otherwise be advantageous. For example, it may be difficult or impossible to employ permanent termination apparatus which requires removal of the stator from the pallet.
In view of considerations such as the foregoing, it is still another object of this invention to provide improved methods and apparatus for temporarily holding the ends of coil wires during and after winding the coils on the poles of a stator.